// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_
#define CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_

#include "content/renderer/media/audio_renderer_sink_cache.h"

#include <vector>

#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "content/common/content_export.h"

namespace content {

// AudioRendererSinkCache implementation.
class CONTENT_EXPORT AudioRendererSinkCacheImpl
    : public AudioRendererSinkCache {
public:
    // Callback to be used for AudioRendererSink creation
    using CreateSinkCallback = base::Callback<scoped_refptr<media::AudioRendererSink>(
        int render_frame_id,
        int session_id,
        const std::string& device_id,
        const url::Origin& security_origin)>;

    AudioRendererSinkCacheImpl(
        scoped_refptr<base::SingleThreadTaskRunner> task_runner,
        const CreateSinkCallback& create_sink_callback,
        base::TimeDelta delete_timeout);

    ~AudioRendererSinkCacheImpl() final;

    media::OutputDeviceInfo GetSinkInfo(int source_render_frame_id,
        int session_id,
        const std::string& device_id,
        const url::Origin& security_origin) final;

    scoped_refptr<media::AudioRendererSink> GetSink(
        int source_render_frame_id,
        const std::string& device_id,
        const url::Origin& security_origin) final;

    void ReleaseSink(const media::AudioRendererSink* sink_ptr) final;

private:
    friend class AudioRendererSinkCacheTest;
    friend class CacheEntryFinder;

    struct CacheEntry;
    using CacheContainer = std::vector<CacheEntry>;

    // Schedules a sink for deletion. Deletion will be performed on the same
    // thread the cache is created on.
    void DeleteLaterIfUnused(const media::AudioRendererSink* sink_ptr);

    // Deletes a sink from the cache. If |force_delete_used| is set, a sink being
    // deleted can (and should) be in use at the moment of deletion; otherwise the
    // sink is deleted only if unused.
    void DeleteSink(const media::AudioRendererSink* sink_ptr,
        bool force_delete_used);

    CacheContainer::iterator FindCacheEntry_Locked(
        int source_render_frame_id,
        const std::string& device_id,
        const url::Origin& security_origin,
        bool unused_only);

    void CacheUnusedSinkIfHealthy(int source_render_frame_id,
        const std::string& device_id,
        const url::Origin& security_origin,
        scoped_refptr<media::AudioRendererSink> sink);

    // To avoid publishing CacheEntry structure in the header.
    int GetCacheSizeForTesting();

    // Task runner for scheduled sink garbage collection.
    const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;

    // Callback used for sink creation.
    const CreateSinkCallback create_sink_cb_;

    // Cached sink deletion timeout.
    // For example: (1) sink was created and cached in GetSinkInfo(), and then (2)
    // the same sink is requested in GetSink(), if time interval between (1) and
    // (2) is less than |kDeleteTimeoutMs|, then sink cached in (1) is reused in
    // (2). On the other hand, if after (1) nobody is interested in the sink
    // within |kDeleteTimeoutMs|, it is garbage-collected.
    const base::TimeDelta delete_timeout_;

    // Cached sinks, protected by lock.
    base::Lock cache_lock_;
    CacheContainer cache_;

    // Weak pointer to be used for delayed sink deletion on |task_runner_|.
    // Pre-created in constructor and is used to post all the delayed tasks.
    // A delayed task can be concurrently posted from any thread the cache is used
    // on, so on-the-flight weak pointer creation with
    // weak_ptr_factory_.GetWeakPtr() can't be used, because it will result in the
    // racy access to the factory.
    base::WeakPtr<AudioRendererSinkCacheImpl> weak_this_;

    // Used to produce |weak_this_| on AudioRendererSinkCacheImpl construction.
    base::WeakPtrFactory<AudioRendererSinkCacheImpl> weak_ptr_factory_;

    DISALLOW_COPY_AND_ASSIGN(AudioRendererSinkCacheImpl);
};

} // namespace content

#endif // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_
